Negative pressure treatment system with heating and cooling provision

ABSTRACT

A method, and apparatus for the controlled acceleration, and/or retardation of the body&#39;s inflammatory response generally comprises a foam pad for insertion substantially into a wound site, a heating, a cooling pad for application over the wound site, a wound drape or sealing enclosure of the foam pad, the heating, and cooling pad at wound site. The foam pad is placed in fluid communication with a vacuum source for promotion of the controlled acceleration or retardation of the body&#39;s inflammatory response. The heating, and cooling provision controls the local metabolic function as part of the inflammatory response.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.11/545,142, filed Oct. 10, 2006, which is a continuation of U.S. patentapplication Ser. No. 09/937,937, filed Oct. 2, 2001, which is a nationalstage application of International Application No. PCT/US00/08759, filedMar. 31, 2000, which claims the benefit of U.S. Provisional ApplicationNo. 60/127,596, filed Apr. 2, 1999. All of the above-referencedapplications are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to the healing of wounds. Morespecifically, the present invention relates to the vacuum assistedclosure of wounds wherein localized heating or cooling is used toaccelerate or retard the metabolic function of the inflammatory systemin order to facilitate wound healing.

2. Description of Related Art

Wound closure involves the inward migration of epithelial andsubcutaneous tissue adjacent the wound. This migration is ordinarilyassisted through the inflammatory process, whereby blood flow isincreased and various functional cell types are activated. Through theinflammatory process, blood flow through damaged or broken vessels isstopped by capillary level occlusion, whereafter cleanup and rebuildingoperations may begin. Unfortunately, this process is hampered when awound is large or has become infected. In such wounds, a zone of stasis(i.e. an area in which localized swelling of tissue restricts the flowof blood to the tissues) forms near the surface of the wound.

Without sufficient blood flow, the epithelial and subcutaneous tissuessurrounding the wound not only receive diminished oxygen and nutrients,but are also less able to successfully fight bacterial infection andthus are less able to naturally close the wound. Until recently, suchdifficult wounds were addressed only through the use of sutures orstaples.

Although still widely practiced and often effective, such mechanicalclosure techniques suffer a major disadvantage in that they producetension on the skin tissue adjacent the wound. In particular, thetensile force required in order to achieve closure using sutures orstaples causes very high localized stresses at the suture or stapleinsertion point. These stresses commonly result in the rupture of thetissue at the insertion points, which can eventually cause wounddehiscence and additional tissue loss.

Additionally, some wounds harden and inflame to such a degree due toinfection that closure by stapling or suturing is not feasible. Woundsnot reparable by suturing or stapling generally require prolongedhospitalization, with its attendant high cost, and major surgicalprocedures, such as grafts of surrounding tissues. Examples of woundsnot readily treatable with staples or suturing include large, deep, openwounds; decubitus ulcers; ulcers resulting from chronic osteomyelitis;and partial thickness burns that subsequently develop into fullthickness burns.

As a result of these and other shortcomings of mechanical closuredevices, methods and apparatus for draining wounds by applyingcontinuous negative pressures have been developed. When applied over asufficient area of the wound, such negative pressures have been found topromote the migration toward the wound of epithelial and subcutaneoustissues. In practice, the application to a wound of negative pressure,commonly referred to as vacuum assisted closure (VAC) therapy, typicallyinvolves mechanical-like contraction of the wound with simultaneousremoval of excess fluid. In this manner, VAC therapy augments the body'snatural inflammatory process while alleviating many of the knownintrinsic side effects, such as the production of edema caused byincreased blood flow absent the necessary vascular structure for propervenous return.

While VAC therapy has been highly successful in the promotion of woundclosure, healing many wounds previously thought largely untreatable,some difficulty remains. Because the inflammatory process is very uniqueto the individual patient, even the addition of VAC therapy does notresult in a fast enough response for closure of some wounds, especiallywhen applied during the occlusion and initial cleanup and rebuildingstages. It is therefore a principle object of the present invention toprovide a method and apparatus whereby the known VAC therapy modalitiesare improved through controlled acceleration of the inflammatoryresponse.

Additionally, and again at least partially attributable to the variancebetween patients, it is possible that a properly initiated inflammatoryresponse may be taken too far, resulting in edema and pain. It istherefore another principle object of the present invention to provide amethod and apparatus whereby the known VAC therapy modalities areimproved through controlled retardation of the inflammatory response.

SUMMARY

In accordance with the foregoing objects, the present invention—a methodand apparatus for the controlled acceleration and/or retardation of thebody's inflammatory response—generally comprises a foam pad forinsertion substantially into a wound site, a heating and cooling pad forapplication over the wound site and a wound drape for sealing enclosureof the foam pad and the heating and cooling pad at the wound site.According to the invention, the foam pad is placed in fluidcommunication with a vacuum source for promotion of fluid drainage whilewarm or cool fluid is circulated through the heating and cooling pad forthe controlled acceleration or retardation, respectively, of themetabolic function portion of the body's inflammatory response.

According to the preferred embodiment of the present invention, aheating and cooling provision is added to the previously known VACtherapy to control the local metabolic function as part of theinflammatory response. By providing localized heating in combinationwith the otherwise ordinary VAC therapy, the overall inflammatoryresponse can be synergistically accelerated to produce rapid capillaryocclusion and earlier initiation of the cleanup and rebuilding stages.Likewise, in the event that the attending clinician determines that theinflammatory response has been over-activated, localized cooling may beprovided in combination with the VAC therapy to retard the body'sinflammatory response without sacrifice of the edema control and otheraspects of the otherwise provided VAC therapy.

In the preferred embodiment of the present invention, the heating andcooling pad comprises a flexible and breathable water layer, generallycomprising two sheets of RF-weldable material. The two sheets of the padare RF-welded together in a waffle-like pattern, wherein a plurality ofapertures is formed between a plurality of channels. The apertures allowthe transpiration of moisture from the patient's skin while the channelsallow the circulation, via a supply tube and a drainage tube, of warm orcool water, as required, through the pad for the heating or coolingthereof.

While the heating and cooling pad may be placed inside or outside of thewound drape during the heating aspect of the present invention, it iscritical that the heating and cooling pad be placed inside of the wounddrape during the cooling aspect of the present invention. In thismanner, condensate formation on the interior of the drape, which maycause the drape's adhesive to loosen and ultimately result in loss ofvacuum at the wound site, can be minimized. In particular, placing theheating and cooling pad inside the wound drape limits the surroundingmoisture content to that existing and generated within the confines ofthe wound site, which is minimized by the suction aspect of the VACtherapy.

Because the cooling aspect of the present invention should beimplemented in this manner and the clinician may indicate the need forcooling at any time after initiation of VAC therapy, the preferredmethod of the present invention comprises placing the heating andcooling pad beneath the wound drape, adjacent the foam pad and woundsite, regardless of whether heating or cooling is initially indicated.Upon placement of the pad, the wound drape is firmly adhered about thesupply tube and drainage tube to prevent vacuum leakage.

Finally, many other features, objects and advantages of the presentinvention will be apparent to those of ordinary skill in relevant arts,especially in light of the foregoing discussions, the following drawingsand exemplary detailed description and the claims appended hereto.

BRIEF DESCRIPTION OF THE DRAWINGS

Although the scope of the present invention is much broader than anyparticular embodiment, a detailed description of the preferredembodiment follows together with illustrative figures, wherein likereference numerals refer to like components, and wherein:

FIG. 1 shows, in partially cut away perspective view, the preferredembodiment of the present invention as applied to a mammalian woundsite.

FIG. 2 shows, in top cross-sectional plan view, the heating and coolingpad of the invention of FIG. 1.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Although those of ordinary skill in the art will readily recognize manyalternative embodiments, especially in light of the illustrationsprovided herein, this detailed description is exemplary of the preferredembodiment of the present invention—a vacuum assisted closure systemwith heating and cooling provision, the scope of which is limited onlyby the claims appended hereto.

Referring now to the figures, the present invention 10 is shown togenerally comprise a foam pad 11 for insertion substantially into awound site 12, a heating and cooling pad 13 for application over thewound site 12 and a wound drape 14 for sealing enclosure of the foam pad11 and the heating and cooling pad 13 at the wound site 12. According tothe invention, the foam pad 11 is placed in fluid communication with avacuum source for promotion of fluid drainage while warm or cool fluidis circulated through the heating and cooling pad 13 for the controlledacceleration or retardation, respectively, of the metabolic functionportion of the body's inflammatory response.

According to the preferred embodiment of the present invention, the foampad 11, wound drape 14 and vacuum source are implemented as known in theprior art, each of which is detailed in U.S. patent application Ser. No.08/517,901 filed Aug. 22, 1995. By this reference, the full disclosureof U.S. patent application Ser. No. 08/517,901 (“the '901 application”),including the claims and the drawings, is incorporated herein as thoughnow set forth in its entirety. Additionally, such a VAC system isreadily commercially available through Kinetic Concepts, Inc. of SanAntonio, Tex., U.S.A. and/or its subsidiary companies.

As detailed in the '901 application, the foam pad 11 preferablycomprises a highly reticulated, open-cell polyurethane or polyether foamfor good permeability of wound fluids while under suction. As alsodetailed in the '901 application, the foam pad 11 is preferably placedin fluid communication, via a plastic or like material hose 15, with avacuum source, which preferably comprises a canister safely placed undervacuum through fluid communication, via an interposed hydrophobicmembrane filter, with a vacuum pump. Finally, the '901 application alsodetails the wound drape 14, which preferably comprises an elastomericmaterial at least peripherally covered with a pressure sensitive,acrylic adhesive for sealing application over the wound site 12.

According to the preferred method of the present invention, thosecomponents as are described in the '901 application are generallyemployed as known in the art with the exception that the heating andcooling provision of the present invention is added to control the localmetabolic function as part of the inflammatory response. By providinglocalized heating in combination with the otherwise ordinary VACtherapy, the overall inflammatory response can be synergisticallyaccelerated to produce rapid capillary occlusion and earlier initiationof the cleanup and rebuilding stages. Likewise, in the event that theattending clinician determines that the inflammatory response has beenover-activated, localized cooling may be provided in combination withthe VAC therapy to retard the body's inflammatory response withoutsacrifice of the edema control and other aspects of the otherwiseprovided VAC therapy.

In the preferred embodiment of the present invention, the heating andcooling pad 13 comprises a flexible and breathable water layer 16,generally comprising two sheets 17 (one not shown) of RF-weldablematerial. The two sheets 17 of the pad are RF-welded together in awaffle-like pattern, wherein a plurality of apertures 19 is formedbetween a plurality of channels 20. The apertures 19 allow thetranspiration of moisture from the patient's skin 21 while the channels20 allow the circulation, via a supply tube 22 and a drainage tube 23,of warm or cool water, as required, through the pad 13 for the heatingor cooling thereof.

While the heating and cooling pad 13 may be placed inside or outside ofthe wound drape 14 during the heating aspect of the present invention,it is critical that the heating and cooling pad 13 be placed inside ofthe wound drape 14 during the cooling aspect of the present invention.In this manner, condensate formation on the interior and near the edgesof the drape 14, which may cause the drape's adhesive to loosen andultimately result in loss of vacuum at the wound site 12, can beminimized. In particular, placing the heating and cooling pad 13 insidethe wound drape 14 limits the surrounding moisture content to thatmoisture level existing and generated within the confines of the woundsite 12, which is minimized by the suction aspect of the VAC therapy.

Because the cooling aspect of the present invention should beimplemented in this manner and the clinician may indicate the need forcooling at any time after initiation of VAC therapy, the preferredmethod of the present invention comprises placing the heating andcooling pad 13 beneath the wound drape 14, adjacent the foam pad 11 andwound site 12, regardless of whether heating or cooling is initiallyindicated. Upon placement of the pad 13, the wound drape 14 is firmlyadhered about the supply tube 22 and the drainage tube 23 to preventvacuum leakage.

While the foregoing description is exemplary of the preferred embodimentof the present invention, those of ordinary skill in the relevant artswill recognize the many variations, alterations, modifications,substitutions and the like as are readily possible, especially in lightof this description, the accompanying drawings and the claims drawnhereto. For example, those of ordinary skill in the art will recognizethat the heating and cooling pad 13 may be constructed in a wide varietyof shapes, sizes and internal structures. Such an alternative embodimentmay comprise the integration of the heating and cooling pad 13 into amulti-layered version of the wound drape 14. In any case, because thescope of the present invention is much broader than any particularembodiment, the foregoing detailed description should not be construedas a limitation of the present invention, which is limited only by theclaims appended hereto.

1. A method for treating a wound comprising: securing a porous pad and abreathable layer in a sealed environment adjacent the wound; maintaininga reduced pressure in the sealed environment; circulating a fluidthrough fluid channels in the breathable layer while transportingmoisture away from the wound through apertures in the breathable layer;and regulating the temperature of the wound with the circulated fluid.2. The method according to claim 1 further comprising alternating thetemperature of the fluid between temperatures greater than thetemperature of the wound and temperatures less than the temperature ofthe wound.
 3. The method according to claim 1 further comprisingproviding the fluid at a temperature greater than the temperature of thewound.
 4. The method according to claim 1 further comprising providingthe fluid at a temperature less than the temperature of the wound. 5.The method according to claim 1 further comprising distributing reducedpressure at the wound through the porous pad.
 6. The method according toclaim 1, wherein the fluid is water.
 7. The method according to claim 1further comprising: alternating the temperature of the fluid betweentemperatures greater than the temperature of the wound and temperaturesless than the temperature of the wound; and distributing reducedpressure at the wound through the porous pad.
 8. The method according toclaim 1 further comprising: placing the breathable layer in contact withthe porous pad.
 9. The method according to claim 1 further comprising:placing the breathable layer in contact with the porous pad; andcovering the breathable layer and the porous pad with a drape to formthe sealed environment.
 10. The method according to claim 1 furthercomprising: covering the porous pad with a drape to form the sealedenvironment; and placing the breathable layer over the drape such thatthe drape is disposed between the porous pad and the breathable layer.11. The method according to claim 10, wherein the drape has an adhesive.12. The method according to claim 1 further comprising: applying areduced pressure to the wound though the apertures.
 13. The methodaccording to claim 1, wherein the breathable layer has a pair offlexible sheets connected to form the fluid channels between the sheetsto receive the fluid, the pair of flexible sheets further including theapertures.
 14. The method according to claim 1, wherein the pair offlexible sheets are connected by RF welds.
 15. The method according toclaim 1, wherein the fluid channels are continuous.
 16. The methodaccording to claim 1, wherein the fluid channels include an inletconfigured for connection to a supply tube and an outlet configured forconnection to a drainage tube.
 17. The method according to claim 1further comprising: regulating the temperature of the wound with thecirculated fluid based on an inflammatory response of the wound.
 18. Amethod for treating a wound comprising: placing a porous pad adjacentthe wound; placing a thermal control element in contact with the porouspad; covering the thermal control element and the porous pad with adrape; applying a reduced pressure to the porous pad; circulating afluid through fluid channels in the thermal control element; andallowing moisture transpiration from the wound through apertures in thethermal control element.
 19. The method according to claim 18, furthercomprising: regulating the temperature of the wound with the circulatedfluid.
 20. The method according to claim 18, wherein the thermal controlelement is at least one of a heating element and a cooling element. 21.The method according to claim 18 further comprising: coupling a pair ofsheets using RF welds to form the thermal control element.